The present invention concerns an arrangement for connecting a syringe to a drug infusion pump.
For drug infusion into the body of a living being, infusion pumps connected to a syringe in a removable manner are currently used.
The known syringes employed in drug infusion pumps typically are disposable syringes. Said syringes include a hollow cylindrical syringe body having a first, tapered open end, or front end, for discharging the drug. A second open end, or rear end, is generally surrounded by connecting means arranged to firmly connect the syringe to the infusion pump in a removable manner. A plunger is housed in the syringe body and is axially slidable for causing suction and injection of the drug through the first end. An example of syringe of the above kind, suitable for being connected to a drug infusion pump, is disclosed in EP 2810673 (A). The known syringes are generally filled before being connected to the infusion pump. Filling of the syringe is generally performed by sucking the drug through the front end of the syringe, by moving back the plunger by means of a control shaft. The shaft is removed before connecting the syringe to the pump.
In some applications, the syringe is commercialized already filled with drug.
The known infusion pumps are devices including a pump body internally housing the electromechanical members intended for pump operation. Said electromechanical members include a sliding rod partially projecting out of the pump body. The forward and backward movement of the rod relative to the pump body is driven by the electromechanical members of the pump. Said electromechanical members include an electric motor, generally supplied with power by a battery also housed within the pump body. The forward movement of the rod causes the forward movement of the plunger of a syringe connected to the pump and the resulting drug discharge from the front end of the syringe. Moreover, the pump body is generally externally equipped with connecting means arranged around the sliding rod and capable of receiving, in engagement configuration, the second end of the syringe body. An example of a drug infusion pump of such kind, suitable for use in association with a syringe, is disclosed in EP 2394682 (A).
As known, such pumps have the advantage of being particularly compact and of being wearable by the user during execution of the usual daily activities. Moreover, since the pump generally is self-powered by means of a battery, the user may wear the pump practically at any moment in the day, for instance also during care of personal hygiene, during open-air physical activity or, more simply, during usual outdoor displacements. In recent times, therefore, the need has arisen to make such pumps watertight, in order to enable use thereof in environments which are particularly wet or where a certain water amount exists, for instance in form of drops during a rainy day or under the shower.
In the known pumps of the kind discussed above, the rod projects out of the pump body through a suitable opening. That opening is one of the possible ways through which moisture and water can penetrate into the pump. Moisture possibly penetrating into the pump can cause damages to the electromechanical members, in particular to the printed circuits and the electronic components associated therewith, and can alter the pump operation, with even serious consequences for the user. In order to prevent that drawback, different measures are currently adopted in the known connecting arrangements for firmly connecting the syringe to the pump in a removable manner. For instance, the sliding rod is surrounded by an expansible bellows made of rubber, which should prevent moisture from penetrating into the pump. An exemplary solution to the above problem is also disclosed in EP 2832389 (A).
Yet, the prior art solutions have proved to be insufficiently reliable. Moreover, bellows expansion when the rod is moved forward to cause drug infusion gives rise to a vacuum condition within the bellows, contributing to suck air and hence moisture from the outside environment.
It is a first object of the invention to solve the problem of how to make the assembly consisting of the infusion pump and the syringe connected thereto watertight.
It is a second object of the invention to solve the above problem with means that are reliable and resistant even after a high number of infusions and consequent syringe replacements.
It is a further object of the invention to provide a solution to that problem, which can be industrially implemented in the pumps and the syringes with limited costs.
The above and other objects are achieved by means of the arrangement for connecting a syringe to a drug infusion pump as claimed in the appended claims.